2TTO Ch5.6

• Biologie
• Middelbare school
• vwo
• Leerjaar 2

5.6 pregnancy

learning objectives

• What is pregnancy and which phases are there?
• What is implantation and why is this process needed for a healthy embryo to form?
• What structures are there to nourish and support the developing foetus? 

Pregnancy

• Pregnancy is the period of development from zygote to birth. 

• Pregnancy takes place in the female reproductive system

Zygote = fertilized egg

When?

7 days after fertilization implantation of the embryo in the uterus lining occurs. The next 9 months the zygote will develop into a baby.

Fertilization happens when a sperm cell meets an egg

In which phase of the menstrual cycle can an egg be fertilized?

1. Phase 1 (day 1-7)
2. Phase 2 (day 7-13)
3. Phase 3 (day 13-28)

On which day in the menstrual cycle is the implantation of the fertilized egg?

1. Between day 5-10
2. Between day 10-15
3. Between 15-20
4. Between 20-25

The first phase: zygote

• A fertilized egg is also called a zygote. 
• The zygote will start dividing into a tiny clump of cells inside the oviduct (the dividing is called cleavage).
• From then on, the dividing zygote is called an embryo. 

zygote -> morula-> blastocyst -> embryo

What is cleavage?
(choose the best answer)

1. cell divisions during which the zygote grows into a tiny hollow ball of cells
2. cell divisions before fertilization
3. cell division during which the embryo grows into the first foetal stage
4. cell divisions during which the zygote grows into an foetus

The second phase: embryo

• When an embryo reaches the uterus, it implants itself into the uterus lining.
• The uterus lining develops into a placenta, which is able to provide the nutrients and oxygen through the umbilical cord to the embryo. Through the umbilical cord the embryo gets nutrients&oxygen in and removes waste&carbon dioxide. 

The umbilical cord is the connection between the mother and the child. Different substances can pass from mother to child through the umbilical cord, like nutrients, oxygen and waste products. However, other substances can pass as well, such as alcohol, drugs and even some viruses. This is why the mother has to pay attention to what she consumes during pregnancy.

Membranes

During the 3rd week of pregnancy two thin membranes start to grow around the embryo: chorion and amnion

Membranes

Together the amnion and the chlorion form the amniotic sac. The amniotic sac is filled with amniotic fluid.

Membranes

In the amniotic fluid the embryo floats.

Explain how the embryo (and foetus) is protected.

Use the words: 'amnion', 'chorion', 'amniotic sac' and 'amniotic fluid'

The third phase: foetus

• After 2 months is the embryo is called a foetus. 
• The next 7 months the foetus will develop further into a fully grown baby.

So the umbilical cord is the connection between the mother and the child. Different substances can pass from mother to child through the umbilical cord, like alcohol, drugs and even some virusses.

Match the different names with the different stages!

Zygote

Embryo

Foetus

Fertilized egg

Stage in which implantation happens

Month 2-9: development into a baby

After .... weeks of pregnancy the embryo is called foetus

1. 8
2. 9
3. 10

Pregnany lasts for ... weeks after fertilisation

1. 38
2. 39
3. 40
4. 41

The earliest moment a neonatal can be given birth to is after ... weeks of pregnancy

1. 10
2. 15
3. 25
4. 35

It can't be be born earlier because ...

1. The lungs are underdeveloped so it cannot breathe
2. The heart can't beat by itself
3. The neonatal does not have teeth in order to eat
4. the mother cannot breast feed the neonatal

The placenta belongs to ..

1. the mother
2. the foetus
3. both mother and foetus

Next lesson

• Make the exercises of paragraph 5.6
• Read paragraph 5.7
• Take notes!